#include <iostream>
using namespace std;

class Person
{
public:
  int m_age;

  void showClassName()
  {
    cout << "this is Person class" << endl;
  }

  void showPersonAge()
  {
    // 报错是因为传入的指针是为NULL
    cout << "age = " << this->m_age << endl;
  }
};

void test01()
{
  Person *p = NULL;
  p->showClassName();
  p->showPersonAge();
}

int main(int argc, char const *argv[])
{

  test01();

  return 0;
}